1. Field of the Description
The present description relates, in general, to methods and systems for use in determining a safety envelope about a moving object, and, more particularly, to methods and systems for use in designing amusement park rides so as to maintain a predefined reach envelope about a ride vehicle as it moves along a ride path (e.g., moves along a length of track or along a defined path for a trackless attraction).
2. Relevant Background
With any amusement park ride, safety is one of the most important design parameters. Particularly, amusement park rides that involve a passenger vehicle rolling along a track, or along a ride path for a trackless attraction, typically are designed to maintain a safety envelope about the vehicle along the entire length of the track. For example, safety standards set by a park operator or industry groups may define a reach envelope for rides that define the amount of space that is free of obstacles (e.g., set or theme elements) about the vehicle. This space or volume is often labeled a “reach envelope” (or passenger reach clearance envelope) and may be thought of as defining a distance from a typical passenger position that should be free of any object that may be contacted or “reached” by a passenger as the vehicle carrying the passenger passes along the track.
Each ride may have a different reach envelope definition, and a single ride may be designed so that different reach envelope definitions may apply along differing portions of the ride track or along differing portions of the ride path. For example, a dark theme ride may be designed with a track that winds itself through a themed environment or set at a relatively slow pace, and the reach envelope may be relatively small as even if contact is made the danger is comparably low. In contrast, a roller coaster may have stretches of track where the vehicle is moving at very high speeds, and a much larger reach envelope may be used for these stretches of track. Further, the same roller coaster may have stretches where the speed is reduced and, likewise, the reach envelope may be smaller in these portions of the ride. Further, the vehicle (or seat) design and/or the passenger restraint design may vary so as to allow different amounts of passenger movements (e.g., a shoulder restraint may make it difficult for a passenger to reach outward from a vehicle while a lap restraint may allow a significant amount of passenger movement). These differing vehicle and/or restraint designs may then be paired with differing reach envelopes, with a smaller envelope used when the passenger is more restrained from reaching outward and so on.
Further, a ride designer may wish to apply a number of reach envelopes to the same stretch of track or a ride path and then let differing “obstacles” be present (or absent) in each envelope. For example, a first envelope may be associated with a small or no reach situation (the envelope defines a relatively small distance about the vehicle), a second envelope may be associated with a passenger gently trying to reach out, and a third envelope may be associated with the passenger really trying hard to reach out (e.g., a teenager may push hard to intentionally try to contact a nearby obstacle). The ride may set or use differing envelopes based on the ride's intended passengers.
In other cases, though, the ride designer may allow “soft” obstacles within the smaller or no reach envelopes such as a cloud of smoke, a spray of water, a curtain, and so on while harder obstacles may only be provided in larger envelopes or, more often, must be placed to be outside of the reach envelopes. The “allowables” or what items can be provided in an envelope typically will vary with the speed of the vehicle along the track. In other words, the ride is designed to provide a physical safety zone around each of the passengers while they are moved through an attraction or ride in a vehicle. This is to protect them from coming into contact with an object that may be harmful. Depending on the passenger's speed relative to the object as well as its distance from the passenger, certain classifications of items can be allowed or disallowed in the region or physical safety zone. With speed, distance, and classification of the object (whether it is hazardous (e.g., hard, sharp, or the like) or benign (soft, rounded, water, smoke, or the like), the ride designer can determine whether the object is allowed in the zone or space about the vehicle.
Presently, reach envelope testing or checking is a very cumbersome and inefficient process. One method of checking reach envelopes involves attaching a large wooden template in the shape and size of the clearance envelope to a ride vehicle, e.g., a planar piece of wood may be attached to the center of the vehicle and arranged to be orthogonal to the direction of travel for the vehicle. Then, the vehicle is slowly moved, such as via a winch, through the ride or attraction. When the physical template hits an object, the vehicle is stopped on the track, and the inspectors (which may include the ride designer) visually assess the intrusion into the envelope. This may involve determining whether the object may be within the envelope (an “allowable”) or whether the object needs to be removed (e.g., cut away a volume of a tunnel or cave wall for a roller coaster, remove a scenery piece in a dark ride, or the like).
There are a number of problems with using such a reach envelope process to check the design of ride as it is being built. The process is slow and cumbersome in part because the templates are large and they obstruct workers' movements and line of sight around the vehicle. Further, since there are different sizes of clearance zones, the process has to be repeated with different sizes and/or shapes of the templates on the vehicle or the template has to be changed out along differing portions of the track. The current technique also requires the actual ride vehicle to be winched around the track, and the vehicle may weigh several tons such that this can be a challenging process to perform safely in a reasonable amount of time.